Config of uninstalled modules gets recorded in config_overlay.deleted

Merged the branch now, since the test passed. Note that I also included a fix for hook_module_preinstall() but that is somewhat theoretical. If a module deleted it's own shipped configuration in its hook_install() then that would have previously not been recorded but should be now. Not including a test for that, though, as that seems a bit far-fetched.

Opening an MR now for the backport to 8.x-1.x and then will release new bugfix versions.

Alrighty, seems all tidy now.

Thanks again! Will release new bugfix versions for this (and the other one) soon, but marking this one fixed for now.

Automatically closed - issue fixed for 2 weeks with no activity.